package state

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"time"
)

type State struct {
	RunID  string    `json:"runId"`
	SentAt time.Time `json:"sentAt"`
}

type Store struct{ dir string }

func New(dir string) Store { return Store{dir: dir} }
func (s Store) Prepare() error {
	dir := filepath.Join(s.dir, "sent")
	if err := os.MkdirAll(dir, 0o700); err != nil {
		return fmt.Errorf("create sent marker directory: %w", err)
	}
	file, err := os.CreateTemp(dir, ".write-check-*")
	if err != nil {
		return fmt.Errorf("check sent marker directory: %w", err)
	}
	name := file.Name()
	if err := file.Close(); err != nil {
		_ = os.Remove(name)
		return fmt.Errorf("close sent marker write check: %w", err)
	}
	if err := os.Remove(name); err != nil {
		return fmt.Errorf("remove sent marker write check: %w", err)
	}
	return nil
}

func (s Store) Has(runID string) (bool, error) {
	_, err := os.Stat(filepath.Join(s.dir, "sent", runID+".json"))
	if err == nil {
		return true, nil
	}
	if os.IsNotExist(err) {
		return false, nil
	}
	return false, fmt.Errorf("check sent marker: %w", err)
}
func (s Store) Mark(runID string) error {
	if err := s.Prepare(); err != nil {
		return err
	}
	dir := filepath.Join(s.dir, "sent")
	body, _ := json.Marshal(State{RunID: runID, SentAt: time.Now()})
	tmp := filepath.Join(dir, fmt.Sprintf(".%s.tmp", runID))
	final := filepath.Join(dir, runID+".json")
	if err := os.WriteFile(tmp, body, 0o600); err != nil {
		return err
	}
	return os.Rename(tmp, final)
}

// Dir 返回状态目录，供调用方复用（例如告警节流状态落盘）。
func (s Store) Dir() string { return s.dir }